Category Archives: Power

I have a cordless drill with rechargeable batteries. The batteries charge completely in about 20 minutes. They are not supposed to stay on the charger for longer than that. However, unless I am standing right there after the charging time, I forget to take the batteries off of the charger.

To fix this problem, I made a timed duplex power outlet out of a countdown timer and a duplex outlet. I plug the timed outlet into a 120v outlet. Then, plug the battery charger into the duplex outlet attached to the timer. Finally, I set the timer to 20 minutes and walk away. (There are more details about the parts and assembly on the Instructable.)

One problem I had is that the faceplate that came with the timer was too wide. It covered the timer and a bit of the duplex outlet. I found a Thing on Thingiverse that uses the Customizer to custom build faceplates that cover from one to five outlets with any configuration. I used it to make a custom faceplate for two outlets with a single hole for the timer on the left-hand side and holes for a duplex outlet on the right-hand side. I printed it on the Makerbot 3D printer using black PLA filament. I used 100% infill to make it solid and durable.

One problem I had with the print was that the raft stuck to the surface in some spots and would not come off. So, there are a few rough looking spots. Another problem is that the hole for the timer knob was a bit too small. I had to drill it out slightly bigger.

After attaching the new faceplate, I used my label maker to print the numbers for the dial.

That’s it. No more ruined batteries due to overcharging. And, it’s portable!

Power? We always need more power! Many months back Joel had an old computer power supply that he modified to use as a cheapo bench power supply. Sure, it doesn’t have all the bells and whistles (and adjust-ability) of a real bench power supply, but since we hate to waste, and love to recycle, it’s a good use of an old power supply.

I learned a lot about power supplies last month when I destroyed the one I use(d) with my RepRap, and in the process I ended up harvesting a few PSUs from old computers we had in the server room at work. I ended up using one of them to build my own project power supply with 5 volt and 12 volt outputs. I grabbed a pair of resistors from the component library to put a load on the supply, and drilled four holes in the case to mount a few posts I got at Radio Shack. I’ve now got plenty of power to power all sorts of powerful projects!

Here you can see it powering up an LED ring light that requires 12 volts. I can also use it to run a small fan when soldering components. The uses for such a power supply are endless! (Well, within the supplied voltage and current anyway.)

American Science & Surplus is selling residential style electric watt hour meters. Awhile back I picked up this analog one from them for $14, but they also have digital ones for less at their tent sale going on this weekend. I finally found some time to play with it and I managed to get it working. I’ll probably turn it into a lamp or something!